JP3259163B2 - Discharge lamp lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device with improved control of the rise of the luminous flux of a discharge lamp such as a metal halide lamp.

[0002]

2. Description of the Related Art When a discharge lamp is used as a headlamp of an automobile, the discharge lamp must be turned on and restarted instantaneously. In the case of instantaneous lighting, a discharge is started by applying a high voltage pulse at the time of starting. Thereafter, it is necessary to immediately start up by supplying a current six times the rated current.

FIG. 7 is a block diagram showing a configuration of a control system of a conventional discharge lamp lighting device for instantaneously lighting a discharge lamp as described above. This control system detects the tube voltage and tube current at the time of starting the discharge lamp by the voltage detection circuit 3 and the current detection circuit 4 using the sensors 1 and 2 and performs correction control at the start of lighting. The stable control circuit 5 and the start control circuit 6 output the set values of the control current when the discharge lamp is stable and the control current when the discharge lamp is started as control signals from the tube voltage of the discharge lamp detected at the time. At this time, the rise correction timer circuit 7 intentionally delays the control immediately after the start.

The PWM control circuit 8 compares a control signal (set value) from the control circuits 5 and 6 with a detected current (tube current) detected at the time of starting, outputs a PWM signal, and controls an inverter output voltage. The circuit 9 controls the inverter output voltage to the discharge lamp according to the PWM signal. Thereby, the discharge lamp can be shifted from the lighting start to the stable state.

[0005] In addition, a rise correction timer circuit 7 is provided to suppress an undershoot or the like in the light emission output when the discharge lamp is turned on instantaneously.

[0006] Here, the discharge lamp in the case of instantaneous lighting is necessary to increase rapidly standing in the initial lighting stage six times the rated current, as described above, the tube voltage by valves own thermal mass rated , The internal temperature is not sufficiently increased, and it takes 30 seconds or more to obtain a stable light emission amount.

FIGS. 8 to 10 show the light beam rising characteristics of the apparatus shown in FIG. 7. FIG. 8 shows the rising characteristics of the D2S type discharge lamp when the rising correction is performed, and FIG. 9 shows the rising correction. FIG. 10 shows the rise characteristics of the discharge lamp when the rise is not performed, and FIG. 10 shows the rise characteristics when the rise correction is performed with the D1 type discharge lamp without an outer bulb.

In the case where the make-up current is controlled only by the detected tube voltage without performing the rise correction, as shown in FIG.
At about 0 second, the tube voltage has already risen, but since the temperature inside the bulb has not yet risen, an undershoot occurs and the luminous flux drops to about 50%. In addition, an outer bulb for cutting off ultraviolet light is provided around the discharge lamp.
In the 2S or D2R type, the influence of the thermal mass appears more remarkably than in the D1 type.

Therefore, as a countermeasure against the above-mentioned undershoot, in addition to the control using the tube voltage, a rising correction timer circuit 7 is provided so that the current falls gradually from a certain tube voltage level, and the light quantity sharply increases. It prevents a serious drop.

FIG. 11 shows luminous flux rising characteristics at tube voltages of 75 V, 85 V, and 95 V when rising correction is performed with a 35 W discharge lamp. As described above, since the rise in the internal temperature is slower than the tube voltage and an undershoot occurs, the rise correction timer circuit 7 performs the current reduction control by delaying the rise from the tube voltage.

FIG. 12 is a diagram showing a control pattern for reducing the current. The hatched portion F in the figure is a portion where the current is added by the timer control, and this is a control delay portion. Then, as time passes, the original characteristics gradually approach.

[0012]

By the way, in the above-described conventional discharge lamp lighting device, for example, the aforementioned D1
In the discharge lamp of the type, the overshoot and the undershoot are relatively small since the thermal mass is small, and as shown in FIG. 10, it is possible to approach a stable luminous flux after 10 seconds after lighting. However, in recent years, D2S and D2R type discharge lamps having an outer bulb for cutting off ultraviolet rays have become mainstream due to a demand for measures against ultraviolet rays.

Since the discharge lamp with the outer bulb has a large thermal mass, the temperature inside the bulb is not easily stabilized, and it takes a longer time for the luminous flux to be stabilized as compared with the D1 type. For example, as shown in FIG. 8, even after a considerable overshoot, the luminous flux is still reduced after 20 seconds. At this time, the light output fluctuates greatly, and excessive overshoot leads to deterioration of the discharge lamp.

[0014] Further, as a standard of a 35 W metal halide lamp, a variation of a tube voltage of ± 17 V with respect to a rated voltage of 85 V is recognized. In the case of controlling with a fixed pattern as shown in FIG. 11, as shown in FIG. 11, a high tube voltage of 95 V has a fast rise and an overshoot is excessive, while a low tube voltage of 75 V has a slow rise and an undershoot occurs. I do. It is considered that there is a difference in the rise due to the difference in the tube voltage because the higher the tube voltage, the larger the applied power for the same current, and the tube temperature rises earlier.

As described above, in the prior art, the rise control is performed for each discharge lamp in the same control pattern. Therefore, there is a large variation in the rise characteristic due to the discharge lamp. If the undershoot is large, the standard may not be satisfied due to insufficient light flux.

The present invention has been made in view of the above-mentioned problems, and has a small overshoot and undershoot, a smooth luminous flux rising characteristic with little fluctuation, and an improved lighting feeling. It is another object of the present invention to provide a discharge lamp lighting device in which the life of the discharge lamp is prolonged.

[0017]

According to the present invention, there is provided a discharge lamp lighting apparatus for correcting and controlling a tube current of a discharge lamp with a different value for each set time at the time of start-up after the start of lighting of the discharge lamp. A rising correction timer circuit having a timer, and a correction area of the timer 1 having a higher time constant as the voltage is higher in accordance with a tube voltage at the time when the discharge lamp is stable estimated after the start of lighting of the discharge lamp . by reducing the correction region of the slow timer 2, also in the timer of the rising correction timer circuit so as to increase the slow correction region of the timer 2 of the time constant less faster correction region of the timer 1 of the time constant as the voltage is lower It has a timer switching circuit for switching.

[0018]

[0019]

FIG. 1 is a block diagram showing the configuration of a control system according to one embodiment of the present invention. The same reference numerals as in FIG. 7 denote the same components. In FIG. 1, reference numeral 10 denotes a plurality of timers (1) and (2), which are sequentially switched at the start-up of the discharge lamp after the start of lighting of the discharge lamp to change the tube current of the discharge lamp. This is a rise correction timer circuit that controls with different values during the set time of each of the timers (1) and (2).

In other respects, the circuit configuration is the same as that of FIG. 7, and the inverter output voltage control circuit 9 is based on the set value of the control current determined by the detection tube voltage of the discharge lamp and the detection tube current of the discharge lamp. It is configured to control the inverter output voltage at startup.

The basic operation of the control system of the discharge lamp lighting device configured as described above is the same as that of the control system of FIG. Control is performed.

FIG. 2 is a diagram showing the luminous flux rising characteristics when the D2S type discharge lamp is turned on instantaneously in this embodiment.
FIGS. 3A and 3B show a comparison between the rise control patterns of the conventional example and the present embodiment. FIG. 3A shows the case of the conventional example, and FIG. 3B shows the case of the present embodiment.

The solid line shown in FIG. 3 (a) is a recommended standard for a 35W discharge lamp. However, if the control is performed as it is, an undershoot will occur. After that, the current reduction control was performed by the timer. A broken line portion in FIG. 7A is an additional portion of the current by the timer control, and this is a delay portion of the control. Then, as the time elapses, the characteristic approaches the characteristics indicated by the solid line in the figure. As a result, an extra current is added to the rising portion where the undershoot has occurred, so that the rising of the optical output is corrected.

However, conventionally, the control is performed by a single time constant timer, and the rising speed of the tube voltage is not constant, so that the undershoot can be corrected, but the overshoot occurs. Could not.

Therefore, in the present embodiment, as shown in FIG. 3B, a control using a plurality of timers is performed to perform a smooth rise control with little fluctuation.

That is, from the start of lighting to the tube voltage of about 40 V at which undershoot begins to occur, the current reduction control is similarly performed in accordance with the tube voltage. The current reduction rate is changed by two different timers (1) and (2). More specifically, the first half of the fast rise time of the tube voltage is controlled by switching to the timer (1) having a fast time constant, and the second half thereof is controlled by switching to the timer (2) having a slow time constant. In the area, the timer (1) with a fast time constant prevents the overshoot from increasing as much as possible.
In a region where the increase in the tube voltage has become slower, the timer is switched to a slower timer (2), and until the light output becomes stable (about 25 to 30 seconds after the start of lighting), the undershoot is not gradually generated so that the undershoot does not occur. Reduce to lighting current. The portion B in the figure is the portion added by the timer (1), and the portion C is the portion added by the timer (2).

The switching points of the timers (1) and (2) are, for example, 60 to 70 V in the case of a standard tube of 85 V, the time constant of the timer (1) is about 20 seconds, and the time constant of the timer (2). Was about twice as good as the experimental result.

As described above, in this embodiment, even a discharge lamp having a D2S, D2R type outer bulb of a metal halide lamp and having a difficult startup control can be turned on instantaneously, and at the same time, overshoot and undershoot occur. Smooth light output rising characteristics with little and constant fluctuations are obtained, and the feeling during lighting is improved.

Further, since there is little overshoot due to overpower, deterioration of the discharge lamp is reduced and the life is prolonged.

Further, in the case of the D1 type discharge lamp, a flatter rising characteristic can be obtained by adjusting the timer.

FIG. 4 is a block diagram showing the configuration of another embodiment of the present invention, and the same reference numerals as in FIG. 1 denote the same components. In the above embodiment, the timers (1) and (2) are automatically switched, but in the present embodiment, the timers (1) and (2) are switched based on a certain condition.

In FIG. 4, reference numeral 11 denotes the timer circuit 1 shown in FIG.
A rise correction timer circuit having timers (1) and (2) having different time constants similar to 0, an integration circuit 12 for integrating a riser tube voltage of the discharge lamp, and a tube voltage at a stable time after the start of lighting of the discharge lamp. Is provided for estimating. Reference numeral 13 denotes a timer switching circuit that switches between the timers (1) and (2) of the rise correction timer circuit 11 according to the estimated tube voltage when the discharge lamp is stable.

Next, the operation will be described. As in the above-described embodiment, when the tube voltage that needs rise correction at the time of lighting the discharge lamp is 4
In the rising tube voltage control region from 0 V to the stable time,
The timer (1) having a fast time constant is used in the first half region where the tube voltage rises still early, and the timer (2) is used in the second half region where the tube voltage rises slowly, so that overshoot and undershoot can be suppressed as low as possible.

At this time, the integrating circuit 12 estimates a stable tube voltage by integrating a rising tube voltage having a large fluctuation at the time of starting, and a timer switching circuit 13 based on the voltage value.
Controls the switching timing of the timers (1) and (2) at the time of rising. As a result, it is possible to obtain a rising characteristic with less fluctuation corresponding to the variation of each tube voltage.

FIGS. 5A and 5B are diagrams showing control patterns for each voltage. FIG. 5A shows a discharge lamp having a low tube voltage of about 70 V, FIG. 5B shows a standard case of about 85 V, and FIG. 10
The case of a high tube voltage of about 0 V is shown. The part D in the figure is the additional part by the timer (1),
E indicates the added portion by the timer (2), and P is their switching point.

As described above, the tube voltage is set to 40 V from the start of lighting.
The current reduction control by the detection tube voltage is performed up to the level, and when the voltage rises to 40 V or more where the rise correction is necessary, the correction timer circuit 11 delays the current reduction and adds the necessary current. FIG.
(B) In the case of a standard discharge lamp of about 85 V, the switching point P of the timer is set to about 60 V, and the control is delayed by the timer (1) having a fast time constant from about 40 to 60 V to suppress overshoot. The delay from 60 to 85 V is delayed by a slow timer (2) to suppress the occurrence of the subsequent undershoot.

In the case of a discharge lamp having a low tube voltage of about 70 V shown in FIG. 5A, the correction area is as short as 40 to 68 V.
Since overshoot hardly occurs and undershoot easily occurs, the correction area of the timer (1) is shortened, and the timer (2)
The switching point P is determined so that the correction region of the above becomes longer.
In the case of a discharge lamp having a high tube voltage of about 100 V in FIG. 5C, the correction area becomes longer at about 40 to 90 V.
The correction area of the timer (1) is lengthened so that excessive overshoot does not occur, the current is reduced as soon as possible, and the correction area of the timer (2) is shortened to the extent that undershoot does not occur.

FIG. 6 shows each voltage (75 V, 85 V) in this embodiment.
(V, 95 V) when the D2S type discharge lamp is turned on instantaneously. As shown in the figure, a smooth rise characteristic with little fluctuation is obtained at each voltage, and therefore, it is possible to sufficiently cope with 85V ± 17V which is the standard of the tube voltage variation of the 35W metal halide lamp. D2 with outer valve
Instantaneous lighting control can be easily performed even for a lamp whose startup control is difficult, such as an S, D2R type discharge lamp.

As described above, in this embodiment, the tube voltage value in the stable state is estimated from the start of lighting of the discharge lamp to the rising tube voltage value at which the rising of the light emission output needs to be corrected. Based on this, the subsequent rise correction control is performed in a form suitable for the tube voltage, so that overshoot and undershoot are suppressed even for each discharge lamp with tube voltage variations, and a stable and smooth Rise characteristics can be obtained.

Therefore, there is no need to adjust the rise of the lighting circuit for each discharge lamp, and a stable rise characteristic can be obtained even if the tube voltage of the discharge lamp rises over time. Also, as in the previous embodiment, the overshoot is reduced, so that the stress on the discharge lamp is small, the life of the discharge lamp can be extended, and the occurrence of undershoot also occurs in the discharge lamp with a low tube voltage. Since the number is small, it is possible to eliminate a problem that the required rising light beam does not satisfy the standard.

Further, when detecting the tube voltage, the EEPR
Since the data and the like at the previous lighting are not stored by using a special IC such as OM, the cost can be reduced, and the overshoot and the undershoot are less likely to occur even at the first lighting after the discharge lamp is replaced. It is possible to obtain excellent rising characteristics.

The present invention is suitable for a lighting system of an instantaneous lighting type using a discharge lamp for vehicles such as D1, D2S, D2R type, particularly a lighting system using a discharge lamp as a headlamp. As well,
In addition, the present invention can be applied to a lighting system of an optical product such as a liquid crystal projector which needs to be turned on instantaneously using a metal halide lamp.

The control system may have various circuit configurations irrespective of analog circuits or microcomputer circuits.

[0044]

As described above, according to the present invention, the timer is switched at the start-up after the start of lighting of the discharge lamp so as to correct the current reduction control. Thus, there is an effect that a smooth luminous flux rising characteristic with less is obtained, a feeling at the time of lighting is improved, and a life of the discharge lamp is prolonged.

Also, there is an effect that appropriate rise control can always be performed irrespective of changes in tube voltage and aging.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a control system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a light beam rising characteristic according to an embodiment;

FIG. 3 is an explanatory diagram showing a rising control pattern according to an embodiment;

FIG. 4 is a block diagram showing a configuration of a control system according to another embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a rising control pattern according to another embodiment.

FIG. 6 is a view showing a light beam rising characteristic of another embodiment.

FIG. 7 is a block diagram showing a configuration of a control system of a conventional example.

FIG. 8 is a view showing a light flux rising characteristic of a conventional example.

FIG. 9 is a view showing a light beam rising characteristic of a conventional example.

FIG. 10 is a diagram showing a luminous flux rising characteristic of a conventional example.

FIG. 11 is a diagram showing a light beam rising characteristic of another conventional example.

FIG. 12 is an explanatory diagram showing a rising control pattern of another conventional example.

[Explanation of symbols]

 3 Voltage Detection Circuit 4 Current Detection Circuit 5 Stable Control Circuit 6 Start Control Circuit 8 PWM Control Circuit 9 Inverter Output Voltage Control Circuit 10 Rise Correction Timer Circuit 11 Rise Correction Timer Circuit 12 Integrator Circuit 13 Timer Switching Circuit

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hisao Hirata 1-1-15-207 Kugenuma Beach, Fujisawa-shi, Kanagawa Prefecture (56) References JP-A-7-65982 (JP, A) JP-A-5-205885 ( JP, A) JP-A-3-98295 (JP, A) JP-A-4-12495 (JP, A) JP-A-4-163887 (JP, A) JP-A-4-342988 (JP, A) Hei 6-82799 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05B 41/14-41/298

Claims (1)

(57) [Claims] 1. A rise correction timer circuit having a plurality of timers for correcting and controlling a tube current of the discharge lamp at different values during respective set times when the discharge lamp rises after the start of lighting of the discharge lamp; According to the tube voltage at the time when the discharge lamp is stabilized, which is estimated after the start of lighting, the higher the voltage, the more the correction area of the timer 1 having a faster time constant and the less the correction area of the timer 2 having a slow time constant. A timer for switching each timer of the rise correction timer circuit so that the correction area of the timer 1 having a shorter time constant is increased and the correction area of the timer 2 having a slower time constant is increased as the voltage is lower. A discharge lamp lighting device comprising a switching circuit.